Modification of Immunogenicity of Leukaemic Cells by DNA Mediated Gene Transfer
The spontaneous AKR leukaemia K36 has been extensively studied in our laboratories. This tumour does not express the H-2Kk gene product and is resistant to T cell cytolysis. The H-2Kk antigen is the restriction element for T cell killing of Gross virus-infected AKR cells . We have now introduced a normal H-2Kk cloned gene c27.2 (M. Steinmetz), together with the G418-resistant plasmid pTCF into this tumour by calcium phosphate- mediated gene transfer. Between 8 and 20 trans-formants per 106 cells were selected in medium containing 800 μ/ml G418. From over 300 trans-formants we selected a series of clones that expressed different amounts of H-2Kk molecule on the cell surface for study. DNA was isolated from each of the selected transformants and analysed by Southern blot. Hybridisation of the plasmid pTCF (vector), or an H-2Kk DNA probe to the blots, showed that each of the transformants contained one to three copies of the exogenous H-2Kk gene.